*{
  margin: 0;
  padding: 0;
}
.tab{
  width: 500px;
  height: 500px;
  margin: 50px auto;
  border: 1px solid black;
}
.tab .nav{
  height: 50px;
  border-bottom: 1px solid black;
}
.tab .nav-item{
  float: left;
  width: 33.33%;
  height: 100%;
  text-align: center;
  line-height: 50px;
  cursor: pointer;
}
.tab .nav-item.current{
  color: #fff;
  background-color: black;
}

.tab .page{
  position: relative;
  height: 450px;
}
.tab .page-item{
  position: absolute;
  left: 0;
  top: 0;
  width: 100%;
  height: 450px;
  line-height: 450px;
  text-align: center;
  display: none;
}
.tab .page-item.current{
  display: block;
}
